Have a look !

No Assurance can be given that any WIFI router N type suggested will fulfill your condition of range "About 800 Feet "
Buy A N type WIFI router with Dual Antenna.

@ essbebe, Fully agree

@ snigdhadeep, I would suggest you to go with Edimax BR-6524n router, It is 300Mbps Broadband router with 3Ant and good coverage capacity. Good post sales support and 3yrs warranty. Installation is easy using Edimax EZmax setup wizards which comes with product as bundled CD.

Further, if you find any dead spots around required Wi-Fi coverage area, (as Wi-Fi coverage depends on many environmental factors which includes obstacls, noise level and positioning of router) you can add up Access point and AP should be used in Universal repeater mode to extend wireless coverage area wirelessly.